Nootschap hanbelmaatschappij oablon



March 15, 1932. M. HCHSTDTER HIGH TENSION CABLE Filed Deo. 27, 19?..6- 2 SheetS-Sheea March 15, 1932. M HCHSTDTER 3,849,624

HIGH TENSION CABLE Filed Deo. 27, 1926 2 Sheets-Sheet 2 i' evacuated in the factory higher working temperatures.

Patented Mar. `15, 1932 UNITED STATES ENT OFFICE NAAMLOOZE VEN- NOOTSCHAP HANDELMAATSCHAPPIJ C'ABLON (CABLON CORPORATION), OF THE BAGUE, NETHERLANDS HIGH-TEN SION CABLE Application led December 27, 1926, Serial No. 157,400, and in Germany January 6, 1926.

The reliability in working of an felectric cable is increased in respect to its tensionstress if its insulating material is put under pressure. This is, up to date, gained by providing, apart from its electrical insulating layer, tubes with permeable walls in the cable for receiving and conducting a liquid, or gaseous pressure medium, placed under pressure at suitable points by outer, mechanical means. v n

The said permeable walls permit an unobstructed and direct development of the hydrostatic pressure of the pressure liquid upon all points f the inner or outer surface of the conductor insulation and also impregnation of the cable already provided with an outer protective covering by the said tubes. On account of the permanent connection between pressure medium and insulating material existing under this arrangement with per.- meable walls, certain difficulties will arise.

The insulating impregnating material has to be identical with the pressure medium, viz. has to be still desirable for electrical reasons. The pressure tubes must furthermore generally be before shipping the cables. The conductor insulation loses hereby its impregnating material partly or wholly a-nd a second impregnation is consequently necessary after the cable has been laid, which takes time and is less reliable.v Impregnation previous to the leadcovering according to the usual method and under utilization of the everywhere existing working equipments, can yhardly be effected with the liquid pressure medium. Employment of an impl-eg# Dating material, differing from the pressure medium, as for instance a thick liquid, is very difficult, as both mediums will later mix in an uncontrollable manner, especially under Impregnating multiple-conductor cables after stranding, offergreat difficulties, viz. the conductors would have to be impregnated singly before stranding.

By employment of the present invention it is possible to eliminate these difficulties. The invention oii'ers consequently great advanliquid under the lowest work- If f ing temperatures. This is however often untages in the employment of artificial pressure 1n cables, particularly in cables of the ordinary production, with common impregnatlng-co-mpound, differing from the pressure medium.

The invention is based upon the perception,

that 1t is not necessary to keep the pressure liquid in bodily contact with the impregnating material of the insulating layer, but that the favourable iniuence of the pressure upon the increase of the working reliability of the cable takes effect even if between pressure medium and insulation an impermeable membrane is provided. The same must however be sufficiently iexible to permit transmission of the pressure of the pressure medium to the insulation and, if possible, uniformly at all points.

According to the invention, suiciently impermeable and suiiiciently flexible layers are arranged between the insulating material proper and the channels for receiving and conducting the pressure medium in the cable. tubes with permeable walls are besides employed inthe pressure channels, it is done for other reasons, for example, mechanical reasons.

Several methods of executing the invention are illustrated by the accompanying drawings, in which ig. 1 is a section of a single-conductor cable with an impermeable layer on the hollow copper conductor. @L

Fig. 2 shows in section a stranded threecore cable with metallized conductors, where- 1n an impermeable layer, (membrane) is provided for the hollow copper conductor of each core.

Fig. 3 is a section through a cable with solid I copper conductors, in which the pressure channels are arranged in the filling spaces. The impermeable layer is located on thesurface of the insulation of the conductors. v

Fig. 4 illustrates a section through a stranded three-core cable with belt insulation and pressure channels of special shape instead of the material for the fillers.

Fig. 5 shows the cross section of a single conductor rcable with the membrane on the surface of the insulation and the pressure channel between this surface and the outer protective covering. Y.

Fig. 6 is a longitudinal section thereof.

Fig. 7 is a section of an armouredsingle- 3 conductor cable with metallized insulation, membrane and a pressure channel according to Fig. 5. f 1

Fig. 8 shows a stranded three-core cable with metallized cores, membrane enclosing u the three metallized cores, and pressure channel between this membrane and the outer protective covering.

Fig. 9 shows a stranded three-core .cable with metallized cores similar to Fig. 2, with u hollow conductors, in which the pressure channels are however not arranged inside of the conductors, but occupr the space ofthe fillers. The membrane is ocatedon the surfaces of the insulated cores.

90 The single conductor cable according to Fig. 1 consists of the metal conductor a, the insulation b and the lead covering e. The conductor a is hollow, the" interior d serves as pressure channel. The active insulation b is se arated from the metal' conductor by a mem rane w.

Manufacturing and laying of this cable can be eifected in the usual manner, viz. a'membrane a: is placed upon the copper conductor.

n a and the insulating material b spun over, whereupon the cable can be impregnated with any desired impregnating material. The lead covering e, is put on thereafter.

The membrane can be made in diii'erent l ways `of one or several layers, if itcomplies with the two-fold condition of the im regnating material in the' insulation b an the pressure medium in thechannel d, i. e. being suiiiciently impermeable and at the same time suiiiciently iiexible.

This membrane a: may therefore consist of conductive or non-conductive material, it may have the shape of a thin cylinder with or without seam, or the shape of a wound tape In the latter case, a paper or textile tape is preferably selected, impregnated with synthetic resin or a similar substance. The tape andthe membrane formed thereby, becomes` impermeable likewise at the overlapped edges of the tape, as they are pasted together under application of heat during drying of the insulating layer b before impregnation of the same. 'Animpermeable layer is thus obtained, which attaches itself as an impermeable 'lexible membrane to the inner surface of the conductor insulation b, as the mem- .brane'consists practically of the same mate- `rial, (paper) of which the insulation b is built up with the exception of the impregnation.

Manufacturing this cablel in well known manner, it diiers from an ordinary singleconductor cable only by the inserted membrane and the hollow space d. Upon lay- .5 ing, the hollow space d caneasily be illed 'ment of a vacuum and heat, or simply by means of warm air bein passed'through.

A continuation of t e pressure channel across the junction d is practically effected through the joint boxes of a cable sectlon.

' The outer pressure generators, for instance pressure-pumps, batteries of gas flasks, etc. by which the pressure of the ressure medium is roduced, are preferab y connected where ca le terminal boxes exist.

Fig. 2 shows the cross-section of a stranded three-core :cable with metallized cores, in which each core is built up according to Fig. 1. f is the double, steel tape armour, the electric conductive layer on the core surilaces, which may be metallized in 'accordance with known methods to render the cable free from ionization. This metallizing is advantageously permeable to permit impregnation. k are the iillers consisting usually ofa jute or similar material.

Production of the entire cable-strand under lead is effected in the usual way as shown the impregnating compound into the channels d during impregnation, as well as diffusion between the compounds in .b and d in operation. It transmits howeverthe pressure of d upon b mechanically, whereby the increase in disruptive strength of the insulation b is produced. Y

The arrangements according to Figs. '1 and 2, when in service, have the disadvantage, that the pressure medium is under high electrical tension, so that corresponding arrangements must be provided` on the pressure generators outside. 'This drawback has been avoided in the methods of execution according to Figs. 3, 5, 6,7, 8 and 9,.as the walls of the pressure channel are grounded. In the arrangement according to Fig. 4, the pressure channels carry only a certain fraction of the electrical working tension.

Fig. 3 shows a stranded three-core cable with lnetallized cores and solid conductors. in which the filler spaces serve as pressure channels and the membrane a; is, according to the invention, arrangedon the surfaces of the cores. Y

Flexible tubes c, permeable forthe pressure medium, are arranged in the filler s aces, they may `consist for instance of spirally wound wire and allow room for conveying the pressure medium. The remaining space of the fillers is occupied by filling material. The permeable tubes and the filling material are however `not essential for carrying out multaneously the purpose of metallizing. InA

this case, illustrated in Fig. 3, the cores may be impregnated uumetallized and afterwards covered blv a. metallizedd paper tape. the metal coating of which is not perforated; and the paper may besides be coated with synthetic resin or impregnated,.so that the overlapped wrapping with this material under subsequent heating becomes pasted together at the overlapped edges and forms a perfectly tight, firmly adhering membrane serving simultaneously as protection against ionization. The adherence at the edges is not however necessary to provide a sutliciently impermeable la er.

)ther methods 'of metall'izing may be employed in place of that above described. If the cores are already in metallized condition, viz with permeable metal surfaces, they are impregnated and the impermeable layer is after impregnation, forV instance, produced by drawing the cores through a suitable liquid or paste, which hardens afterwards. A paper, or textile tape impregnated with synthetic resin may for instance be wound over the permeable metallizing.

,IfY the conductive contact between the metallized core surfaces and the outer lead covering is lto be maintained, suitable arrangements `have to be made. The liquid, or paste coating may for instance after impregnation be removed from such partsl of the core surface as project somewhat consequent to the overlapped metallizing. If a special impregnated tape is applied, the desiredv contact may be obtained-by insertion of metal wires in the tape in known manner.

Three or more of the thus finished single cores are now stranded with the necessary fillers h., and the tubes c, the lead coverin e and armouring f being placed in positlon thereafter.

The thus manufactured cable is treated after laying similarly as described above. If

moved from the pressure channels, and dryconsequently very simple.

In Fig. 4, an ordinary stranded three-core .cable with belt insulation z' and wire armour f is illustrated, in'which the vpressure channels are contained within impermeable flexible tubes fr, having `the shape of the filler spaces and occupying their space, so that other filling material is not required. rlhe pressure tubes :c can of course not till their purpose perfectly, as they contact upon only a part of the insulation surface, otherwise, this cable may be made in the usual manner and impregnated. The cable according to Figs. 5 and 6 is not armoured. The single conductor cable, according to Fig. 7, is however equipped with double, steel -tape armour. Fig. 5 shows an impermeable membrane as on the surface of the insulation, the pressure channel d being located between this membrane and the outer lead covering e and kept free for the pressure medium by a spiral c made of sutliciently resisting material.

In Fig. 7 it is presumed, that the Isingle conductor cable is made free from ionization, viz that it carries a metallization g, besides having the membrane In Fig. 8 is illustrated an armoured three- .core cable with,metallized cores a b, g, in

which the membrane ai is provided on the outer surface of the cable under the lead covermg. i

The pressure channel d is again between the core and the lead covering, kept free by the spiral c.

The cables according to Figs. 5 and 8 can be made in theordinary way and impregnated, the membrane being applied after impregnation. The cable is handled after layf ing, as described above.

In Fig. 9 another embodiment of an armoured, stranded three-core cable with metallized cores is illustrated, similar to that of Fig. 3. Its pressure channels occupy the whole space of the fillers and are limited by the metallized membranes w on the surfaces of the cores and the lead covering c. The copper conductors a are hollow. This cable is preferably produced dry under lead and armoured. The strands b can then be dried and impregnated from the hollow metal conductors and this may be doneeither simultaneously with the filling of the pressure chambers d, or not. The impregnating compound for the insulation b can be identical with, or different from `the pressure medium in the channels d.

This mode of execution according to Figure 9 offers therefore great freedom in respect of selecting the impregnating materialv and pressure medium and enables the pressure to be exerted from both sides of the insulation, from outside and inside, if a sullicientlv thin liquid medium is employed in the high tension conductor a, as wellas in the channels d. This mode of execution has how-V ever-in the latter instance the disadvantage of a second impregnation after layingl the cable. If in the yhollow conductors a, the 1usual imprcgnating compound is however employed, this drawback is.l eliminated.

In the described modes ofexecution, the armour f opposes the .pressure exerted by the pressure medium towards the outside. In the absence of armour, the lead covering'may be substituted by an alloy of such stren h that it withstands this pressure, or the ca le may be drawn throughsuiiiciently resisting pipes or ducts.

'The pressure channels d of the constructions according to Figs. 3, 5, 6, 7, 8 and 9 require no special connectorslin the joint boxes, but they may be simply in free communication with the interior of the boxes, if this interior spacel of the joint boxes is filled with the pressure medium. The joint boxes must of course in such case be constructed pressure proof. This oii'ers to the joint boxes like advantage for their own working reliability as pressure does for the cable itself.

In the foregoing description I have spoken,I

with regard to certain figures of the annexed signature.

drawings, of the use of the invention for metallized cables according to known processes, but it is to be understood that the invention is capable of quite general application and that it can be employed in connection'with all high tension cables of whatever compo-' sition or mode of manufacturing.

l. A high tension cable comprising a conductor, insulating material for said conductor, a pressure channel having an impervious flexible/Wall in engagement with and adapted to be pressed againstl said insulating material, and a pressure medium in said channel,

against said insulating material, and apres-l sure medium in said channel. r

5. The method of manufacturing and installing high tension cables which comprises assembling conductors and insulating material with an impervious exible wall on the insulating mater1al,impregnating the in-` sulating material, providinga pressure channel 1n pressure commumcatmn wlth sald Wall,

and filling said pressure channel with a pressure medium independently of the operation of impregnating said vinsulating. material.

6. A. high tension cable comprising eonductors, insulating material therefor, an impervious flexible wallsurroinding said insulating material, a pressure channel in` which said conductors with their insulating material and said wall are disposed,.and a.

covering, and a pressure medium in said pressure channel. l

In testimony whereof I have .aiiixed my 4i'ianfrni HCHSTTER.

ves

2. A high tension cable comprising a conductor, insulating material for said conductor, impregnating material for said insulating material, a pressure channel havingian impervious flexible wall in engagement with and adapted to be pressed against said insulating material, and a pressure medium in said channel different from said impregnat ing material.

3. A high tension cable comprising a coni l ductor, insulating material orsaid conductor, a pressure channel having an impervious flexible `Wall in the form of a sheath onV said insulating material, adapted to be pressed against said insulating material, and a pressure medium in said channel.

4f.I A high tension cable comprising a conduc-tor, insulating material for said conduc-l 

